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Old Time Radio MP3 CDs Secret Revealed
The Secret of Cheap Vintage Radio CDs
Imagine being able to enjoy nearly 48 hours of Philip Marlowe on a single CD. If you do a search on Ebay, youget the opportunity. The one I'm talking about is 96 episodes of Philip Marlowe available for $3.89 plus shipping At first, it seems to good to be true. After all, how can you get 96 episodes on one CD.
The first thing to realize is that you're talking about a CD that's full of MP3s, not an audio CD that you can put in a CD player. In essence, you're buying a series of audio files put on a CD. It can be done. The question is how well . For 96 half hour shows on a single CD, the answer is not as well as you might like. It's all about the bit rate.
This chart from podcast provider Lisbyn is a good illustration. A half hour program at the higher end of the quality (128 kbps) is 28.8 MB. On the lower end (32 kbps), it's only 7.2 MB. Keeping in mind that a CD has 700 MB of space, this means that the 96 half hour episodes of Philip Marlowe are encoded at 32 kbps.
I should say that this sound quality isn't unacceptable. In fact, I listen to a lot of old time radio shows with that sound qualty and enjoy them. However, for those who like great audio, you may find this quality a disappointment.
What difference can bit rate make? Here are three sound files to compare. All three are episodes of "Yours Truly Johnny Dollar" from 1950 with Edmund O'Brien in the tital role:
Here's a 32 kbps recording, "The Pearl Carassa Matter"
Here's a 64 kbps recording, "The Harold Trandem Matter"
Here's a 128 kbps recording, "The Earl Chadwick Matter."
It should be noted that some sellers also go below the 32 kbps sound quality and that's when sound can get a bit hairy. However, it's usually pretty easily divisible. If someone's selling 300 shows on a single CD, run. You're not going to get even decent quality.
Remember every CD-R has 700 MB of data storage, every normal single-layer DVD-R disc holds 4.7 GB. So if someone is selling 227 episodes of a half hour pogram on 3 CDs, that suggests about 9.25 MB per episode, which means most, if not all of the episodes will be in the lower 32 kbps range. Of course, even if the math works out better If the same 227 episodes were on a DVD, that would equal more than 20 MB an episode which could suggest at least mid-range quality, but you'd want to e-mail the seller to be sure, as they may downsample to 32 kbps by habit.
This isn't to say, you have to hold out for a high quality CD, but you should be aware what you're buying when you buy it, so you know if you're paying for low or high quality audio because that will determine whether the price is fair.
If you want to avoid the lowest quality available, you can buy from an mp3 CD seller who can clarify their exact bit rate. Truth be told, every series that is sold on CD or DVD can be found free to download on the Internet (such as the Old Time Radio section of the Internet Archive.) and you can find each episode for free by using a search engine. For the absolute audiophile who can't stand anything other than best, I'd reccomend purchasing CDs from a company such as Radio Archives which provides high quality remastering. Of course, these are quite a bit higher priced than ebay options, but if you really are picky about sound quality, you get what you pay for.